Power transmission pump or motor



March 5, 1946. K. R. HERMAN POWER TRANSMISSION PUMP OR MOTOR- Original Filed Dec 24; 1938' INVENTOR l KENNETH HERMAN Patented Mar. 5, 1946 POWER TRANSMISSION PUMP 0R MOTOR Kenneth R. Herman, Franklin, Mich., assignor to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Original application December 24, 1938, Serial No. 247,579. Divided and this application May 16, 1942, Serial No. 443,220

4 Claims. (Cl. 103126) This invention relates .to power transmissions, particuarly to those of the type comprising two or more fluid pressure energy translating devices oneof'which mayfunction as a pum and another as' a fluid'motor. The present application is a division of applicants copending application Serial No. 247,579, filed December 24, 1938, now Patent No. 2.3101178, issued February 2, 194,3.

The invention is particularly concerned with a fluid pressure energy translating device operable a's'a pump or a motor and which i particularly adapted for use in fluid power transmission systems aboard aircraft- .As is well known, devices for such service are required to be of maximumlightness and reliability.

i It is an object ofthe present invention to provide an improved gear pump or motor particularly adapted for aircraft service which is overable at high' pressures with va long life and high reliability and which is relatively light in weight.

Further objects and advantages of the present invention will be apparent from'the following description, reference being had to the accompanying drawing wherein a preferred form of. the

present invention is clearly shown.

In the drawing: t

Figure 1 is a longitudinal cross section of a gear pump or motor incorporating a preferred form of the present invention.

Figure 2 is a section on line 2-2 0I Figure 1.

Figure 3 is a section on line 33 of Figure 1.

.Figure 4 is a section on line 44 of Figure 1.

Referring now to Figure 1, there is provided a pump body member ID having a gear receiving chamber 12, the shape of which is shown by dotted lines in Figure 2. The gear chamber is provided with liners I4 rigidly secured to the body 10. End plates l5'and l6 are removably secured to the faces of the body l0 and have rigidly secured thereto facings l1 and I8 which complete the lining of the gear'chamber l2.

A drive shaft 20 is journalled on an anti-friction bearing 22 provided with an oil seal 23 in the end plate l5 and at its righthand end is iournalled in a bearing 24 in the end plate l6. Keyed to the shaft 20 is a drive gear 26 which lies within one-half of the gear chamber l2. Meshing with the gear 26 is an idler gear 21 ournalled on a fixed shaft 28 positioned in bores 30and 32 in the end plates l5 and tively.

Referring to Figures 2 and 3, the end plate I6 is provided with suction and delivery passages 34 and 36' which connect to the spaces 35 and 31 I6, respec- As seen in Figure 3, the conduits 46 and 48 com municate with the right end face of the plate I6 by drilled passages 50 and 52. The latter are disposed non-symmetrically-about a plane passing through the axes of the suction and delivery passages 34 and 36. A bore 54 is also formed in the end plate l6 connecting with the bearing 24 ,and' forming a drain passage for oil seepage.

This bore communicates with amilled groove 58 in the right end face of the plate l6.

Secured to the end plate I6 is an end cap 58 having incorporated therein a reliefvalve. The cap 58 has through conduits 68 and 62 which connect with the passages 34 and 36, respectively, and provide at the rlghthand end a means for connecting the device as a whole to suction and delivery piping.

The conduit has a branch extension 64 and the conduit 62 has a branch extension 66 both of which are connected by a vertical passage 68 having a seat 10 at its upper end. iii-relief valve ball 12 rests on the seat 10 and is urged downwardly by a spring 14 the upper end of which is received in an adjusting screw 16 threaded into the end cap 58. ,Suitable lock and sealing nuts 18 and are provided on the screw '16.

The extension 64 communicates with the slot 56 by a drilled connection 82. The extension 64 also communicates with the passage 58 by a drilled conduit 84 while the extension 66 communicates with the passage 52 by a drilled conduit 86.

The end cap 58 is provided with four bolt holes 88 which are symmetrically positioned about a will register with the slot 56 since, as seen in Figure 3, the latter extends below the central point above mentioned. In the position opposite to that shown, however, the register between conduits 84 and 86 on the one hand and passages Ii and 62 on the other hand will be transposed.

In constructing a device of this character for operation under pressures beyond one thousand pounds per square inch, the materials of which the various parts are made are largely determlnative of success or failure. It is necessary that the clearances both at the tips ofthe gear teeth with the peripheral walls of the chamber and at the end faces of. the gear teeth with the end walls of the chamber be maintained within extremely close limits over a wide range of temperature changes.

For purposes of lightness it is desirable to make the body member Ill and the end plates I and it of cast steel which gives requisite strength with the relatively thin wall sections illustrated. It is likewise essential that the gears be made of hardened steel in order to withstand the heavy loads imposed on them. It is undesirable, however, to

run steel against steel in any bearing surface so that the provision of a lining for the gear chamber formed from a suitable bearing material is necessary. All commercially available bearing materials, however, have a markedly greater coefficient of thermal expansionthan that of steel which ordinarily would prevent the use of such a liner in a steel body or at least would, if used, seriously impair the operation of the device over a wide range of operating temperatures.

Thi dimculty is overcome in the .present invention by forming the linings H, H and is as a relatively thin coating of the order of one-sixteenth of an inch which is intimately secured to its respective backing member along all parts of the abutting surfaces. Preferably the lining is formed by application of the bronze material in surface of the steel member is covered with a built-up layer of bronze. The bronze may then be machined down to a smooth surface of required thinness. In this way it is assured that even though the coemcienc of expansion of the accuse cantly diflerent from that of the housing, said layer being intimately bonded to the body over the entire surface of contact and being at least one sixty-fourth of an inch thick but sumciently thin and elastic to follow the expansion and contraction of the body with changes of temperature rather than to follow the expansion and contraction dictated by the coeflic'ient of expansion of the lining material.

'2. A gear pump or motor comprising in combinations sectional steel body having a gear chamber formed therein, inlet and outlet ports communicating with said chamber, a pair of hardened steel intermeshing gears rotatably mounted in said chamber, and a lining for said chamber comprising a layer of bronze having a coeflicient of thermal expansion significantly different from that ofthe housing, said layer being intimately bonded to the body over the entire surface of contact and being at least one sixty-fourth of an inch thick but sufficiently thin and elastic to fol- 7 low the expansion and contraction of the body with changes of temperature rather than to follow the'expansion and contraction dictated by the small "gobs by a welding process until the entire i. A gear pump or motor comprising in combination a sectional steel body having a gear chamber former therein, inlet and outlet ports communicatingwith said chamber. apair of hardened steel inter-meshing gears rotatably mounted in said chamber, and a lining for said chamber comprising a layer of non-ferrous bearing metal having a coefficient of thermal expansion signifi.

coefficient of expansion of the lining material.

3. A gear pump or motor comprising in combination a sectional steel body having a gear chamber formed therein, inlet and outlet ports communicating with said chamber. a pair of hardened steel intermeshing gears rotatably mounted in said chamber, and a lining for said chamber comprising a layer of non-ferrous bearing metal having a coefficient of thermal expansion significantly higherthan that of the housing. said layer being intimately bonded to the body over the entire surface of contact and being at least one sixty-fourth of an inch thick but sufficiently thin and elastic to follow the expansion and contraction of the body with changes of temperature rather than to follow the expansion and contraction dictated by the eoemcient of expansion of the lining material.

4. A gear pump or motor comprising in combination a sectional steel body having a gear chamber formed therein, inlet and outlet ports com- 1 municatlng with said chamber, a pair of hardened. steel intermeshing gears rotatably mounted in said chamber, and a lining for said chamber comprising a layer of non-ferrous bearing metal having a coefficient of thermal expansion sig. niflcantly different from that of the housing. said layer being deposited on the surface of said chamber in intimate contact over the entire surface of contact and being at least one sixty-fourth of aninch thick but suiliciently thin and elastic tofollow the expansion and contraction: of the body with changes of temperature rather than to follow the expansion. and contraction dictated by the coeflicient of expansion of the lining material.

KENNE'I'HRHIBMAN. 

